Be a detective for a day: How to detect falsified interviews with statistics

Abstract

Interview falsification has been occurring for decades on different levels but is still often insufficiently detected and treated in practice. This is a severe issue as interview fabrication can have major effects on final estimates. This article aims to draw attention to this important topic, with focus on falsification by telephone (CATI) interviewers, and to provide National Statistical Offices with a base for a data-driven, mostly automatic tool written in the statistical software R to detect interviewers with irregularities in their answers or their time patterns. The further application of traditional methods, e.g. recontact or test calls, is far more effective with such focused samples than with random samples. As revealing conspicuous interviewers sometimes feels like detective work, this article intentionally has a little detective side story. Together we will look at the means of evidence, investigate it with various methods, filter out the conclusive evidence and conclude how to close the case.